植物的新型内源激素—油菜素甾醇类

1970年,美国学者米切尔(Mitchell)等人从油菜花粉中分离出一种具有很强生理活性的物质,称为油菜素,它能显著地促进豆类植物幼苗的生长。到1979年,美国格罗夫(Grove)等人证明了油菜素是一种混合物,提纯后具有高活性的结晶物,并鉴定了分子立体构型,定名为油菜素内酯。十多年来,有关油菜素内酯的研究发展很快,目前,至少有24种与油菜素内酯有关的化合物,从植物体内分离出来,它们被总称为油菜素甾醇类。研究发现油菜素甾醇类的     

植物体中油菜素内酯的信号转导

介绍了油菜素甾醇类突变体的代谢分析和相应突变基因及其产物的分子生物学 ,油菜素内酯的合成及其调节 ,相继发现的一些假设的油菜素内酯的受体和受油菜素甾醇类调节的基因等方面的研究进展 ,并提出一些油菜素内酯信号转导和调节相应基因表达的模式     

生长素与其他信号之间的相互作用

就生长素与其他植物激素(赤霉素、细胞分裂素、乙烯和脱落酸)以及油菜素甾醇类和光信号转导途径之间相互作用的研究进展作了评述和展望.     

响应面法优化纤维素酶提取草菇中甾醇类化合物的工艺

草菇具有抗菌、抗肿瘤、抗氧化等功效,为提高草菇中甾醇类成分的提取率,通过响应面法优化草菇中甾醇类化合物的提取工艺。根据Box-Benhnken设计原则,以酶解温度、酶解pH、酶浓度进行3因素3水平研究,使用磷硫铁显色法测定草菇中甾醇类化合物的含量并计算其提取率,通过Design-Expert. V 8.0.6软件分析获得最佳提取条件。结果表明:草菇中甾醇类化合物最佳提取条件为酶解温度64.75℃、酶质量浓度8.46 mg/mL、酶解pH 4.4,此时甾醇类化合物的提取率为1.401%。通过酶提取法提取后,草菇中甾醇类化合物的提取率增加,为草菇中活性成分的深入研究提供基础依据。     

油菜素甾醇类植物激素的研究进展

本文介绍油菜素甾醇类植物激素在植物中的存在,结构与活性的关系,命名,检测方法,生理功能,与核酸和蛋白质代谢的关系及其在农业上的应用方面的研究进展。     

蜂蜡中油菜素甾醇的生理活性

油菜素甾醇类(Brassinosteroids)是近年来较为引人注目的一类具有甾醇结构的植物生长物质。它们较广泛地分布于植物花粉、未成熟种子、枝、叶、花及虫瘿等处,不但具有多种生理功能,而且很可能被应用于农业生产。油菜素甾醇以江西产蜂蜡为原料制备的三十烷醇原粉里分离出,在化学组成和结构方面与合成的油菜素内酯相似。作者采用黄化水稻叶片倾斜法,对该提取物进行了生物活性鉴定。本文仅报道这方面的试验结果。     

新一类植物激素—甾族油菜素

甾族油菜素(Brassinosteroid,Bs)是七十年代发现的第一类天然甾体植物激素,具有其独特的生物学意义,已引起国内外学者的广泛兴趣。本文就甾族油菜素的发现,生物活性、生理效应及其作用机理和农业应用等方面作一概述,以期为这些方面的深入研究和甾族油菜素的广泛应用提供参考。一、油菜素内酯的发现早在1968年,日本的丸茂晋吾从蚊母树的叶片中分离提取到一种比生长素活性高的物质,它能够引起水稻第二叶片的弯曲,但在《农业生物化学》(Agri,Biol.Chem)杂志上发表后,并     

油菜素甾酮的^125I标记及其生物活性

油菜素甾酮是合成油菜素内酯的前体,它具有７０％以上的油菜素内酯生物活性。油菜素甾酮的Ｂ环－６－酮基经与盐酸羧甲基羟胺反应后得到油菜素甾肟,当浓度为１０μｍｏｌ／Ｌ时用水稻叶片倾斜法其生物活性比对照增加６０％以上;当浓度为２μｍｏｌ／Ｌ时能促使黄瓜下胚轴伸长,比对照增加２０％。用油菜素甾肟与油菜素内酯或油菜素甾酮一起处理黄化水稻幼苗,测得水稻叶片与叶鞘之间的倾斜角度介于它们单独处理之间。用氯胺－Ｔ法     

油菜甾醇类化合物国际讨论会概况

1990年在美国和德国相继召开了两次油菜甾醇类化合物国际学术讨论会。由于两次会议相隔甚近,不少与会者在两次会议上的报告颇多重叠之处。在不长的时间里已经聚集了一支人数众多的研究队伍,有人在会上把与会者称之为“Brassinist”。在美     

油菜素甾酮的~（125）I标记及其生物活性

油菜素甾酮（ｂｒａｓｓｉｎｏｓｔｅｒｏｎｅ）是合成油菜素内酯（ｂｒａｓｓｉｎｏｌｉｄｅ）的前体,它具有７０％以上的油菜素内酯生物活性。油菜素甾酮的Ｂ环－６－酮基经与盐酸羧甲基羟胺反应后得到油菜素甾肟,当浓度为１０μｍｏｌ／Ｌ时用水稻叶片倾斜法测得其生物活性比对照增加６０％以上;当浓度为２μｍｏｌ／Ｌ时能促使黄瓜下胚轴伸长,比对照增加２０％。用油菜素甾肟与油菜素内酯或油菜素甾酮一起处理黄化水稻幼苗,测得水稻叶片与叶路之间的倾斜角度介于它们单独处理之间。用氯胺－Ｔ法制备１２５Ｉ－组胺,再与油菜素甾肟结合。先用黄瓜幼苗下胚轴伸长法初步筛选活性组份,再用水稻叶片倾斜法鉴定活性,表明Ｒｆ０．９３处的组份能使水稻幼苗叶片的倾斜活性增加２５％,其放射性比强为７３．８ＧＢｑ／ｍｍｏｌ。     

油菜内酯类似物(BRs)的生物合成与信号传导引起的植物矮化

植物体内的BRs生物合成突变或者感受BRs失调导致植物矮化。本文介绍了BRs的生物合成途径和感受途径相关的基因及其突变型,从分子水平上阐述了这些矮化类型与BRs的关系,并就BRs促进细胞伸长的机制作了一些探讨。     

Brassinosteroid-Mediated Stress Responses

Brassinosteroids (BRs) are a group of naturally occurring plant steroidal compounds with wide-ranging biological activity that offer the unique possibility of increasing crop yields through both changing plant metabolism and protecting plants from environmental stresses. In recent years, genetic and biochemical studies have established an essential role for BRs in plant development, and on this basis BRs have been given the stature of a phytohormone. A remarkable feature of BRs is their potential to increase resistance in plants to a wide spectrum of stresses, such as low and high temperatures, drought, high salt, and pathogen attack. Despite this, only a few studies aimed at understanding the mechanism by which BRs promote stress resistance have been undertaken. Studies of the BR signaling pathway and BR gene-regulating properties indicate that there is cross-talk between BRs and other hormones, including those with established roles in plant defense responses such as abscisic acid, jasmonic acid, and ethylene. Recent studies aimed at understanding how BRs modulate stress responses suggest that complex molecular changes underlie BR-induced stress tolerance in plants. Analyses of these changes should generate exciting results in the future and clarify whether the ability of BRs to increase plant resistance to a range of stresses lies in the complex interactions of BRs with other hormones. Future studies should also elucidate if BRI1, an essential component of the BR receptor, directly participates in stress response signaling through interactions with ligands and proteins involved in plant defense responses.     

Regulation of photosynthesis by brassinosteroids in plants

Brassinosteroids (BRs) regarded as plant hormone are a class of naturally occurring polyhydroxylated sterol derivatives present in all plant species. Overall growth of the plant relies on the very basic and important process of photosynthesis. BRs are found capable of preventing the loss of photosynthetic pigments either by activating or inducing the synthesis of enzymes involved in chlorophyll biosynthesis. BRs play important role in maintaining PS II efficiency by stabilizing D1 protein. It overcomes the stomatal limitations and elevates the efficiency of photosynthetic carbon fixation. BRs also act at various levels of light and dark reactions leading to enhanced carbohydrate synthesis. Therefore, it becomes important to focus and collect information related to various effects of BRs on photosynthesis and its related attributes. The present review deals with the effect of BRs on photosynthesis under normal as well as stressful conditions.     

Brassinosteroid transport

Brassinosteroids (BRs) are steroidal plant hormones that are important regulators of plant growth. These compounds are widely distributed throughout reproductive and vegetative plant tissues. This raises the question of whether or not BRs are transported over long distances between these tissues. Several lines of evidence indicate that this is not the case. Exogenous BRs move only slowly, if at all, after application to leaves; grafting BR-deficient mutants to wild-type plants has no phenotypic effect; removal of the apical bud or mature leaves does not reduce BR levels in the remaining internodes; and, in tomato, wild-type sectors do not substantially alter the growth of BR-deficient sectors when the two types are together in a variegated leaf. Although BRs do not undergo long-distance transport they may influence long-distance signalling by altering auxin transport. At the cellular level, BRs do appear to be transported. The enzymes for BR biosynthesis appear to be located within the cell, and to be associated with the endoplasmic reticulum, in particular. BR reception, on the other hand, is thought to occur on the exterior cell surface. Therefore, BRs must move from the interior of the cell to the exterior, where they are perceived by the same cell or by neighbouring cells. The existence of a feedback system, whereby bioactive BRs negatively regulate their own biosynthesis, provides further evidence that individual cells are able to both perceive and synthesize BRs.     

水稻中一个油菜素内酯不敏感突变体的图位克隆

油菜素内酯(brassinosteroid, BRs)是一类重要的植物激素,在植物的生长发育过程中发挥重要的调节作用。BRs的信号转导研究在双子叶植物拟南芥中已取得重大进展,但在单子叶植物水稻中,BRs的信号转导途径尚不很清楚。本研究从水稻T-DNA插入突变体库中筛选出一个叶片直立突变体el(erect leave mutant)。该突变体与野生型植株相比,叶夹角减小。遗传分析显示,el的突变性状由一对显性基因控制。该基因经图位克隆定位于水稻第5染色体引物InDel3和InDel4之间,物理距离为700 kb。本研究明确了一个水稻BRs不敏感突变体的表型特征及遗传规律,为进一步研究水稻BRs信号转导调控机制奠定基础。     

BRs在植物响应非生物胁迫中的作用

油菜素甾体(brassinosteroids,BRs)是植物界普遍存在的一类多羟基化的植物甾体激素,不仅调节植物的生长发育过程,还参与植物对生物和非生物胁迫的响应.概述了BRs的生物合成途径以及信号转导途径,重点阐述了BRs参与非生物胁迫应答的分子机制,展望了BRs未来的研究方向,为深入理解BRs介导的非生物胁迫调控网...     

Physiological and molecular mechanisms of brassinosteroid-induced tolerance to high and low temperature in plants

Brassinosteroids (BRs) are plant hormones that were isolated for the first time in the 1970s. This group currently includes more than 70 compounds that differ in their structure and physiological activity. BRs are present in plants in a free form or in the form of conjugates. BRs are known as plant growth regulators, but they also play a role in the plant response to environmental stresses. In the case of plants that are exposed to low/high temperature, exogenous BRs can counteract growth inhibition and reduce biomass losses as well as increase plant survival. BRs show a multidirectional activity in regulating the metabolism of plants exposed to extreme temperatures. The following BRs actions can be distinguished: changes in membrane physicochemical properties, regulation of the expression of selected genes (including stress-responsive genes), as well as indirect effects on metabolism through other hormones or signalling molecules (such as hydrogen peroxide). This review summarizes the current knowledge about the effects of BRs on the physiological and biochemical processes that occur in plants during exposure to low or high temperatures.     

Brassinosteroid levels increase drastically prior to morphogenesis of tracheary elements

As the first step toward understanding the involvement of endogenous brassinosteroids (BRs) in cytodifferentiation, we analyzed biosynthetic activities of BRs in zinnia (Zinnia elegans L. cv Canary Bird) cells differentiating into tracheary elements. The results of feeding experiments suggested that both the early and late C6-oxidation pathways occur during tracheary element differentiation. Gas chromatography-mass spectrometry analysis revealed that five BRs, castasterone, typhasterol, 6-deoxocastasterone, 6-deoxotyphasterol, and 6-deoxoteasterone, actually existed in cultured zinnia cells and culture medium. Quantification of endogenous BRs in each stage of tracheary element differentiation by gas chromatography-mass spectrometry exhibited that they increased dramatically prior to the morphogenesis, which was consistent with the idea that BRs are necessary for the initiation of the final stage of tracheary element differentiation. Moreover, the proportion of each BR in culture medium was quite different from that in cells, suggesting that specific BRs are selectively secreted into medium and may function outside the cells.     

Brassinosteroids Regulate Growth in Plants Under Stressful Environments and Crosstalk with Other Potential Phytohormones

Brassinosteroids (BRs) are an important group of plant steroidal hormones that are actively involved in a myriad of key growth and developmental processes from germination to senescence. Moreover, BRs are known for their effective role in alleviation of stress-induced changes in normal metabolism via the activation of different tolerance mechanisms. Efforts to improve plant growth through exogenous application of BRs (through different modes such as foliar spray, presowing seed treatment, or through root growing medium) have gained considerable ground world over. It has been widely demonstrated that the exogenous application of BRs to stressed plants imparts the stress tolerance mechanisms. In BR-induced regulation of physio-biochemical processes in plants, interaction (crosstalk) of BRs with other phytohormones has been reported. This crosstalk may fine-tune the effective roles of other hormones in regulating stress tolerance. The multifaceted role of BRs consolidated so far has reflected their immense potential to help plants in counteracting the stress-induced changes. The effects of introgression and up- and down-regulation of BR-related genes reported so far to improve crop productivity have been presented here. Strong evidence exists that BRs are involved in signal transduction particularly in the regulation of the mitogen-activated protein kinase (MAPK) cascade, which in turn is involved in controlled development, cell death, and the perception of pathogen-associated molecular pattern (PAMP) signaling. How far BRs are involved in signal transduction pathways operative under stressful environments has also been comprehensively discussed in this review.     

Estimation of the Gelatinization Temperature of Noodles from Water Sorption Curves under Temperature-Programmed Heating Conditions

Both free and conjugated brassinosteroids (BRs) in the pollen and anthers of Erythronium japonicum Decne. were investigated. As a free form of BRs, typhasterol was identified by GC-MS. Polar conjugated BRs occurred only in the anther, and non-polar con-jugated BRs occurred both in the pollen and mainly in the anther.

BR parts of acid hydrolysis of the former were identified to be teasterone (major) and castasterone (minor). Those of alkaline hydrolysis of the latter were identified to be typhasterol (major) and teasterone (minor).